Dynamo-electric machine



Feb. 27, 1923. 1,446,861. J. SLEPIAN.

DYNAMO-ELECTRIC MACHINE. FILED MAY 23, p919.

WITNESSES: INVENTQR I Jase 7h Slap/an I BY 1 ATTORNEY Patented Feb. 27, 1923.

UNITED STATES PATENT OFFICE.

JOSEPH SLEPIAN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSE ELECTRIC 6: MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

DYNAMIC-ELECTRIC momma.

Application file'd May 23,

To all whom it may concern:

Be it known that I, JosnPH SLEPIAN, a citizen of the United States, and a resident of Wilkinsbur in the county of Allegheny and State of ennsylvania, have invented a new and useful Improvement in Dynamo- Electric Machines, of which the following is a specification.

My invention relates to dynamo-electric machines, and it has special relation to provision of means, in the machines of the character described, which shall serve to annul the counter-rotational component currents which tend to flow therein.

In unbalanced-current machines, such as single-phase generators, single-phase rotary converters, single-phase synchronous motors, phase balancers, phase converters, etc., counter-rotational currents tend to be established therein, and it has heretofore been common to annul the magnetic effect of such counter-rotational-component currents by placing a damper winding on the machine, the effect of the currents which are inductively set up in such damper winding being to substantially cancel the magnetic effect of the currents which flow. It is apparent, however, that the magnetic effect of these currents is but imperfectly cancelled, thus requiring a counter-rotational voltage to drive them through the machine, and this counter-rotational voltage represents the unbalance on the polyphase circuit to which the machine may be connected. Moreover, since the induced currents which annul the magnetic effects of the counter-rotational currents are in a separate winding, there is no annulment of the heating effect of these currents inthe armature proper.

, One object of my invention, therefore, is to provide machines of the character described with means which shall effectively annul the counter-rotational component currents which tend to flow in the windings without the use of the above described damper windings. That is, I intend to cancel the counter-rotational currents in question in the same winding in which they are incipient.

\Vhile my improved dynamo-electric machines may be used as any one of those machines which are mentioned above, I find that the invention is better understood, as well as most simply explained, in connection 1919. Serial No. 299,242.

with a machine used as a phase balanoer and converter.

In the accompanying drawing, therefore, the single figure illustrates, diagrammatically, a machine constructed in accordance with my invention, and the connections whereby it is interposed between two systems of different phase numbers.

It is desirable to select the loads on the several phases of a polyphase-distributing system soas to prevent excessive unbalancing of the phase voltages and currents. Unless such care is exercised, the transmission system will not operate economically and its ultlmate load capacity will be considerably reduced. Moreover, polyphase apparatus designed for balanced voltages and currents will be adversely affected when connected to an unbalanced polyphase system. For instance, undesirable temperatures may develop in portions of the polypllaseapparatus unless such apparatus is specially designed to carry unbalanced currents. Again, emergency conditions frequently demand that two or more polyphase systems be interconnected to effect an interchange of electrical energy between them. But it is objectionable and ineflicient to do this when one of the systems is considerably unbalanced because the unbalanced system will reflect its unbalanced conditions to any satisfactorily balanced system which may be connected to it.

It is well known that, when a phase converter is connected to a single-phase system and supplies current, in quadrature relation to the current existing in that system, to one phase of a polyphase system, the other phase of which. derives power directly from the single-phase source, unbalancing component currents flow in the phase converter and, since their magnetic effects are only imperfectly cancelled, tend to unbalance the voltages of the polyphase system. It is, therefore, highly desirable to so combine the phase-balancing function with the phase-converting function, in the system as above described, that the unbalancing component currents shall be precluded from reaching and unbalancing the voltage on the polyphase system.

Another ob'ect of my invention is'to provide phase-balancing means, of the character above mentioned, which may also serve as a phase converter, and to associate with such phase-converting machine, means which will be instrumental in affording a path of very low impedance for the unbalancing component currents which tend to enter the polyphase system.

In furtheranceof such object, ll find that the use of a bflancing and convertin ma chine in which the normal rotationa currents and the unhalancing component currents tend to (to-exist in the same winding and in which means are rovided for sub stan-tially annulling the tlbw of the unbalancing currents directly in the winding of the machine, permits of the employment at a much smaller apparatus than the ordinary phase converter. Therefore. ll propose to utilize a machine having rotary converter characteristic-s, since I have discovered that, due to the cancellation of currents in the armature of such machine. the combined functions of phase conversion and subsequent balancing are obtained with one machine of relatively small capacity, as compared with the phase converter and balancing devices of ordinary form.

A sin 'le-phase system is shownat 1, and a polyphase system is indicated by the leads 2-8. interposed between the two systems is a machine 3 of the rotary converter type, having an armature winding 4 connected to commutator bars 55 and to slip rings 66, the slip rings being connected to. quadrature points by the taps 7--7. For purposes of convenience, l have shown the machine 3 as provided with two split poles 8 and 9 and with commutating poles 10, 11, 12 and 13. Connections are made, by means of leads 14, from the single-phase source to certain of the slip rings 6 through brushes 15, and, by this connection, the armature winding 4 of the machines is supplied with power from the single-phase source 1. Leads 16 are connected, through slip rings 17 and the tap connect-ions 77, to quadrature points on the armature winding 4 and permit of the derivation of power of a different phase position from that supplied by the system 1 from the machine 3. This power is fed to one phase of the polyphase system 2. while the other phase of that system is sup-plied with power directly from the single-phase source through leads 18.

Brushes 19 and 20 bear upon the commutator bars 5 in such manner that they connect points of different potential which tends to force current through the lead 21, closed-circuiting the brushes 19 and 20 through a source of electromotive force 22. In this connection, it should be observed that the source of electromotive force 22 is here shown as a battery merely for nrposes of illustration, and, as will hereinaiter appear, there are other devicesof such character as will permit alternating-current to pass but weasel will develop a continuous electromotive force which may be used at this point. Brushes 23 and 24: bear upon the commutator 5 at points of substantially zero potential and are closed-circuited through a lead 2.5.

Assume now that it is desired to use the machine 3 as a phase splitter in order that the polyphase system redpresented by the leads 2 may be supplie with polyphase power through the intermediary of said machine from the single-phase source 1. As usual, one hase of the polyp-hase system is supplied directly from the singlephase source through the leads 18. The other phase of the polyphase system, here shown, for purposes of illustration, as a quadrature phase, is supplied with power from the slip rings on the machine 3 which are connected to quadrature points with'respect to the connection points of the other slip rings.

We have then a tendency for counterrotational currents to flow in the armature winding 4, and it is the elimination of these currents and the consequent complete removal of their voltage-inducing influence on the polyphase system 2 which we desire to efi'ect. Viewing the machine from the commutator end, it is apparent that the commutation of the normal rotational currents which are set up in the machine will result in direct currents tending to flow through the brushes 19 and 20, the lead 21 and the source of clectromotive force 22. The commutation of the counter-rotational currents, on the other hand, will result in doublefrequency currents being drawn from all the brushes and, as hereinbefore pointed out, paths of very low impedance are provided for such double-frequency currents by the closed circuiting of the brushes, pair by pair.

In accordance with the fundamental principle of machines ,of this character, there will be a substantial cancellation of the currents flowing in through the slip rings or, in the case just considered, the counter-rotational currents which tend to exist in the armature, will be annuled by those doublefrequency currents which are drawn out through the brushes. In other words, by my invention I avoid the use of a separate damper winding in all those machines in which counter-rotational currents tend to exist to the detriment of balanced operation. That is to say, by using a machine having rotary-converter characteristics, I find that the cancellation function, which is exerted by the particular windings and connections in such a machine results in the counterrotational currents being killed in the windings in which they have their incipiency.

ltwill be seen that, according to my invention, ll provide external shunt paths, in-

\ cluding the oommutating-pole windings, for the undesirable circulating armature currents, and by makin the impedance of the.

external paths less t an the impedance of the shunted portions of the armature windings, I divert the larger part of the objectionable currents. from the armature, thereby reducing the heating.

Such current cancellation makes it possible to use a machine of relatively smaller capacity than the ordinary phase converter which would otherwise be required, since the aforesaid current cancellation is instrumental in eifectively reducing the heating of the armature conductors, thus reducing the amount of active material required in the machine.

As hereinbefore sug sted, the machine is likewise capable o functioning as a single-phase generator. Under such conditions of operation, it is driven from any suitable mechanical connection, and the single-phase power is derived from two of the slip rings, the specific two. rings which are used being immaterial. Of course, the polyphase system 2 would not longer be connected to the machine. On the other hand, it it is desired to use the machine-as a phase balancer only, it may be attached to the polyphase system 2, as shown in the illustration, the single-phase system being assumed as not connected thereto during this operation.

Still another field in which I find the use of my improved machine beneficial in securing desirable results, is that of the singlephase rotary converter. We may assume that the machine shown in the figure is used as a rotary converter, if we imagine a load connected in parallel to the source of electromotive force 22, and further assume that the rotary is fed with single-phase alternatin current powerfrom the source 1, the other two slip rings not bein connected to any polyphase system. H retofore, the operation of single-phase rotaries has always presented more or less difiiculties because of the pronounced counter-rotational currents existing in the armature of such machines and the consequent necessity of applying a heavy damper winding to the pole faces. By the use of my invention, the

,use'of such damper windings is avoided and,

since the counter-rotational currents are cancelled directly in the armature circuits, the weight and size of a single-phase rotary converter for a given capacity are materially reduced.

Returning, for a moment,to the consideration of the source of electromotive force 22,

it should be understood that such a source through unimpeded. In this connection, I do not desire to be limited to the use of a battery to obtain the opposed electromotive force or the direct current. However, it is welhto point out that the use of a battery is quite desirable, since it functions as an ener -storing and restoring device and, there ore, materially assists in the phase converslon. Moreover, since the battery for this purpose supplies only alternating-current, the direct current bein a matter of voltage only, the question of the quantity of active material, which is so important in an ordinary storage batte is of little import here. From a consideration of the properties of a storage battery, it is apparent that, when the alternating-current supply voltage is high, the battery will absorb energy and, when the alternating-current supply voltage is low, this energy will be returned to the circuit; thus, the use of a storage battery at this point is instrumental in preserving regulation and e ualizes the power drawn from the supply p ase.

While I have pointed out the effect of employing a machine constructed in accordance with my invention in several different fields of operation, it is obvious that many other adaptations of the same may occur to those skilled in the art and I desire, therefore, that my invention shall be construed as broadl as possible and that it be limited only by t e scope of the appended claims or by the teaching of the prior art.

I claim as my invention:

1. A dynamo-electric machine subject to polyphase counter-rotational line-frequency currents and polyphase means for conductively cancelling said currents directly in the winding in which they are incipient.

2. A dynamo-electric machine having an armature winding subject to counter-rotational line-frequency currents and polyphase means connected to said armature winding for directly damping the counterrotational currents.

3. A dynamo-electric machine having an armature winding subject to counter-rotational line-frequency currents, polyphase means for 'commutating said counter-rotational currents, and means whereby the polyphase currents resulting from said commutation are made to cancel the counter-rotational currents directly in the Winding in which they are incipient.

I. A dynamo-electric machine comprising a winding subject to counter-rotational linefrequency currents, commutating means for said currents, and means providing a path of relatively small impedance for the currents obtained by the commutation of said counter-rotational currents.

5. A dynamo-electric machine having a winding subject to counter-rotational currents, and means connected to said winding whereby polyphase double-frequency currents are obtained and whereby the doublefrequency currents thus obtained are permitted to flow freely.

6. A dynamo-electric machine comprising a winding subject to normal rotational and counter rotational line frequency currents and means for commutating both of said currents, said meanscomprisingcommutator bars connected to said winding and brushes bearing on said bars, those brushes through which direct-current tends to flow being connected through a source of counter-electromotive force and the'other brushes being short circuited.

7. A dynamo-electric machine comprising a winding subject to normal rotational and counter-rotational line-frequency currents, means for cvomniutating both of said currents comprising commutator bars connected. to said winding and brushes bearing on said bars, and means in circuit with those brushes through which direct-current tends to flow for substantially preventing said flow but, at the same time, offering a very low-impedance path to the flow of the commutated counter-rotational currents.

8. A phase converter and balancer comprising an armature winding adapted to be connected to an unbalanced polyphase system, and means conductively associated with said winding for'ofi'ering a path oi relatively small impedance for the counter-rotational currents which tend to unbalance the polyphase system.

9. A phase balancer comprising a winding, means for supplying power of one phase number thereto, means for deriving another phase therefrom, whereby counterrotational currents are set up in said winding, means for commutating both the normal and the counter-rotational currents in said winding, and means for substantially preventing the flow of the direct-currents ob tained by said commutation, said means, at the same time, offering a path of very low impedance to the other currents obtained by said commutation.

10. A phase balancer and converter comprising a winding, slip, rings connected thereto for supplying power to, and deriving power from, said winding, whereby bal ancing component currents are set up in said winding, means for commutating said currents comprising commutator bars connected to said winding and having brushes bearing thereupon, the dorushes deriving currents of double the frequency of the balancing component currents therefrom, and means for reducing to a very low value the impedance odered to the flow of said last-- named currents.

weasel which consists in .commutating them and thereafter deriving the commutated currents 'other in the dynamo-electric machine.

12. A dynamo-electric machine having an armature winding subject to normal rotational and counter-rotational line-frequency currents, commutator bars connected with said winding, a polyphase brush system associated with said commutator bars, means for maintaining said brush system stationary in space with respect to the rotating field of said normal rotational currents, whereby direct currents tend toflow in certain of said brushes by reason of said normal rotational current-flow, and whereby symmetrical polyphase double-frequency currents tend to flow in said brushes by reason of said counter-rotational current-flow, and means providing a low-impedance path for said double-frequency currents but offering a relatively high impedance to said direct currents.

13. A dynamo-electric machine having an arvin space with respect to the rotating field of said normal rotational currents, whereby direct currents tend to flow in certain of said brushes by reason of said normal rotational current-flow, and whereby symmetrical polyphase double-frequency currents tend to flow in said brushes by rea' son of said counter-rotational current-flow, and energy storing and restoring means pro-- viding a low-impedance path for said double-frequency} currents but offering a rel-- atively high impedance to said direct cur-- rents.

14:. A dynamo-electric machine having a relatively rotating armature winding sub-- ject to normal rotational and counter-rotational line-frequency currents, commutator bars connected with said winding, a relatively stationary polyphase brushsystem associated with said commutator bars, a relatively stationary field member, means for causing the magnetic flux to enter and leave said field member in definite places, whereby the rotating field of said normal rotational currents tends to remain stationary .with respect to said field member, whereby direct-currents tend to flow in certain of said brushes by reason of said normal rotational current-flow. and whereby symmetrical polyphase double-frequency currents tend tocflow in said brushes by" reason of said counter-rotational current-flow, and means providing a low-impedance path for said double-frequency currents but ofi'eringa rel-. atively high impedance tosaid direct currents.

' 15. A dynamo-electric machine having a relatively rotating armature Winding subject to normal rotational and counter-rotational line-frequency currents, commutator bars connected with said Winding, a relatively stationarypolyphase brush system associated with said commutator bars, a relatively stationary field member, means for causing the magnetic flux to enter and leave said field'n'iember in definit places, whereby the rotating field of said normal rotational currents tends to remain stationary with respect to said field member, whereby direct-currents tend to flow in certain of said brushes by reason of said normal rotational current-flow, and whereby "symmetrical polyphase double-frequency currents tend to flow in said brushes by reason of said counter-rotational current-flow, and external circuits connected to said brushes, said circuits includingv a direct-current translating device connected to one pair of brushes in which said direct currents tend to flow, and said circuits providing a polyphase path offering a relatively low impedance to said symmetrical double-ire quency currents but offering a relatively high impedance to such direct currents as tend to flow therein.

16. The combination with a single-phase system and a direct-current system, of a d name-electric machine having a relativ rotating armature winding connected with said single-phase system, commutator bars connected with said winding, a relatively stationary polyphasebrush system associ ated With said commutator bars, a relatively stationary field member, means for causin the magnetic flux to enter and leave said field member in definite places, whereby the rotating field of said normal rotational currents tends to remain stationary with respect to said field member, whereby direct-currentstend to flow in certain of said brushes by reason of said normal rotational currentflow, and whereby symmetrical pol phase double-frequency currents tend to fibw in said brushes by reason of said counter-1c JOSEPH SLEPIAN. 

